Expert Report

Understanding Climate's Influence on Human Evolution (2010)

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Improved understanding of how past climate may have influenced human evolution could be dramatically enhanced with an international cross-disciplinary research program to improve the sparse human fossil and incomplete climate records, and the link between the two. Climate and fossil records suggest that some events in human evolution -- such as the evolution of new species or migration out of Africa -- coincided with substantial changes in African and Eurasian climate. This raises the intriguing possibility that environmental factors affected or controlled our species' evolution. By altering the landscape, past changes in climate may have exerted pressures that led to genetic selection and innovation in humans. But because both the human fossil record and our understanding of past climate conditions are incomplete, the details of how past climates influenced human evolution remain unclear. The report recommends several research initiatives over the next 10 to 20 years, including a major effort to locate new fossil sites, a comprehensive effort to collect more data to reconstruct past environments, a major investment in climate modeling experiments for the key time intervals and regions that are critical for understanding human evolution, and an enhanced public outreach effort that takes advantage of broad public interest in both human evolution and climate change.

Key Messages

A comprehensive, integrated scientific drilling program on land, in lakes, and in ocean basins surrounding the regions where hominins evolved is needed to address questions about changes in the earth system at a level of detail fine enough to characterize relatively short duration events and processes.

A major exploration initiative to locate new fossil sites and to broaden the geographic and temporal sampling of the fossil and archaeological record is recommended.

A major investment is recommended in climate modeling experiments for the key time ¬intervals and regions which are critical for under¬standing human evolution.

Models could be developed for the specific regions and specific key time periods that bear on potential connections between environmental changes and hominin evolution and dispersal; such models would aid understanding of how change in certain “boundary conditions” like sea-level changes affected climate in specific regions.

Science has provided a general understanding of the timing of major events in human evolution, but a paucity of fossils, particularly over the most interesting periods of rapid evolutionary change, has made it difficult to interpret what has influenced or controlled these events.

There is a general understanding of African and Eurasian climate history at a broad scale, but this climate record generally lacks specifics and details about factors that potentially impacted how early humans lived, and in particular does not adequately reflect local differences in past climates.